The tongue and groove logs are connected with 10 inch black log boss screws and 3/8 inch by 10 inch lag bolts as shown. Butt joints as shown in the 2nd picture are drilled (3rd picture) and sealed with caulking and a 3/4″ wood doll stick (4th picture). Black gaskets are shown on the tops of the tongue to form a seal when inserted into the groove of the next log.